The present invention relates to boring tools for underground boring, and more particularly, it relates to pneumatic impact operated boring tools for use with horizontal boring machines during horizontal boring operations for placement of utility lines and the like.
Pneumatic impact-operated boring tools are well-known in the art. U.S. Pat. No. 3,756,328 issued to Sudnishnikov et al. discloses one such device. Typically, pneumatic impact-operated boring tools are used for burrowing holes in soil, particularly horizontal or near horizontal passages for installation of utility lines when trenching is undesirable. An example of such usage would be for the installation of services underneath an existing structure, such as a driveway or highway, where installation of the line by traditional open cut methods would be impractical. In this situation, the pneumatic impact-operated boring tool is launched from a pit on one side of the structure and is advanced to a receiving pit on the opposite side of the structure.
As the name implies, such boring tools function by impact. The tools possess a striking member (striker) slidable within a cylindrical housing. The striker delivers impacts on a surface at the front end of the housing. This impacting motion within the tool itself causes the soil around the tool to compact away from the nose of the housing, thus forming a hole. The tools are typically driven by a compressed air source. As the compressed air flows through the tool, the striker will be driven in a reciprocal motion generating a series of rapid impacts against the front of the tool housing, causing it to be driven through the ground.
Utility service lines to be installed may either be inserted into the hole formed by the piercing tool, or may be pulled into the hole behind the tool as it operates. Alternatively, pneumatic piercing tools have also been used to install rigid service lines such as steel lines by driving the steel lines into place.
It is occasionally desirable to retract the piercing tools from the borehole being formed. For example, if the piercing tool encounters an obstruction in the soil such as a rock or stone or deviates from the desired path or is damaged in any way, quick withdrawal of the tool from the borehole may be necessary. Most tools are designed to facilitate this retraction by having a mode wherein the striker impacts the rear of the tool causing a retrograde progression of the tool within the borehole.
Thus, reversible impact-operated boring tools are also well-known in the art. U.S. Pat. No. 4,683,960 issued to Kostylev et al. discloses such a device. The prior art discloses various means for accomplishing the reverse motion. In the older designs, the shift from the forward operation mode of the tool to the reverse/withdraw mode is accomplished in any one of the following ways. Some require interrupting the pressurized fluid supply. Others require manipulation of the hose supplying the pressurized fluid to the tool, either by rotating the hose or by pulling it back. Still others require both the interruption of the pressurized fluid supply and the manipulation of the hose.
However, there are several disadvantages associated with these processes. For example, when the pressurized fluid supply is interrupted and the tool is therefore momentarily shut off, the tool may not restart when the pressurized fluid supply is recommenced. In tools requiring hose manipulation, when the hose is flexible, it is often difficult to relate the degree of rotational motion of the hose at the surface to the degree of rotational motion at the tool itself, which may be some distance away. In addition, cave-ins of the hole wall can bind the hose, making it difficult to rotate the hose, or preventing it altogether. Consequently, it is often difficult to reverse the operation of the tool, or to be certain of the direction of operation.
In the more recent designs, the mechanism of shifting the pneumatic tool from forward to reverse is somewhat simplified. U.S. Pat. Nos. 5,172,771 (""771 patent) and 5,327,636 (""636 patent), both issued to Wilson and both incorporated fully herein by reference, disclose such a device. In Wilson""s ""771 patent, a second air hose was added to act as a control mechanism for switching the tool from forward to reverse. Pressurizing the control hose caused a valve mechanism in the tool to move to a forward position, creating the forward movement of the pneumatic tool. Releasing the pressurized air from the control hose caused the valve mechanism to move to a rearward position, resulting in a reverse/withdrawal movement of the tool. However, the valving mechanism in the tool of the ""771 patent is complex, and difficult to assemble, requiring assembly of several parts such as a pre-load spring, snap ring, etc. for valve containment. Additionally, the valving mechanism of the ""771 patent is rigid in terms of deflection perpendicular to the longitudinal axis of the tool body. This inherent rigidity of the valving member makes the tool more prone to stalling if the tool body is deflected along its longitudinal axis by contact with an underground obstacle.
Due to the complexity presented by the current means for the reversing operation of impact-operated boring tools, and the increased labor and time associated with servicing the various component parts, an alternate simpler mechanism for switching a pneumatic piercing tool from forward to reverse operation is needed.
In one aspect, the invention relates to an impact-operated, ground-penetrating tool powered by a primary supply of pressurized fluid, and controlled between a forward operating mode and a reverse operating mode by a second supply of pressurized fluid. The tool comprises a housing, a striker, a manifold, a primary inlet tube, a valve chamber, and a control sleeve. The housing has a front end, a rear end, and body. The body of the housing defines an interior operating chamber with an inner surface, an exhaust conduit to provide fluid communication between the interior operating chamber and the outside of the tool, a forward striker surface, and a rearward striker surface.
The striker is reciprocally supported within the interior operating chamber of the housing between the forward and rearward striker surfaces. The striker has a forward end, a rear portion terminating in a rear end, and a striker body defining an interior striker chamber. The rear portion of the striker sealingly engages the inner surface of the interior operating chamber to divide the operating chamber into a forward operating chamber and a rearward operating chamber. The rearward operating chamber is continuous with the exhaust conduit. The striker body has at least one striker port to provide fluid communication between the forward operating chamber of the housing and the interior striker chamber.
The manifold is located near the rear end of the housing and comprises a primary conduit connectable to the primary fluid supply and a secondary conduit connectable to the secondary fluid supply. A primary fluid inlet tube extends from the primary conduit of the manifold. Additionally, the valve chamber comprises a front valve chamber and a rear valve chamber, the rear valve chamber being in fluid communication with the secondary conduit in the manifold.
The control sleeve has a rear portion terminating in a rear end, a front portion, and an interior sleeve chamber defining a passage between the rear portion and the front portion. The front portion of the control sleeve is slidably and sealingly supported inside the rear portion of the striker. The rear portion of the control sleeve is slidably and sealingly supported on the primary fluid inlet tube at least partially inside the valve chamber. The control sleeve provides continuous fluid communication between the primary fluid inlet tube and the interior striker chamber, so that in response to supply of primary fluid the striker reciprocates between a forward position and a rearward position. In the forward position, the striker port is open between the interior striker chamber and the forward operating chamber. In the rearward position, the striker port is open between the forward operating chamber and the rearward operating chamber and the exhaust conduit.
Finally, the rear portion of the control sleeve includes a nodular lobe inside the valve chamber that sealingly engages an inner wall of the valve chamber and divides the valve chamber into the front valve chamber and the rear valve chamber. The nodular lobe of the rear portion of the control sleeve is movable between a forward position in response to pressurization of the rear valve chamber and a rearward position in response to depressurization of the rear valve chamber. This causes the front portion of the control sleeve to move between a forward position in which the striker hits the forward striker surface as it reciprocates and a rearward position in which the striker hits the rearward striker surface as it reciprocates.
In another aspect, the invention relates to an impact-operated, ground-penetrating tool powered by a primary supply of pressurized fluid, and controlled between a forward operating mode and a reverse operating mode by a second supply of pressurized fluid. The tool comprises a housing, a striker, a means for operably connecting the primary fluid supply, a valve chamber, a means for operably connecting the secondary fluid supply and a control sleeve. The housing has a front end, a rear end, and body. The body defines an interior operating chamber with an inner surface, an exhaust conduit providing communication between the interior operating chamber and the outside of the tool, a forward striker surface and a rearward striker surface.
A striker is reciprocally supported within the interior operating chamber of the housing between the forward and rearward striker surfaces. The striker has a forward end, a rear portion terminating in a rear end, and a striker body defining an interior striker chamber. The rear portion of the striker sealingly engages the inner surface of the interior operating chamber to divide the interior operating chamber into a forward operating chamber and a rearward operating chamber. The rearward operating chamber is continuous with the exhaust conduit and the striker body has at least one striker port to provide fluid communication between the forward operating chamber and the interior striker chamber.
The means for operably connecting the primary fluid supply connects the primary fluid supply to the interior striker chamber. Additionally, the means for operably connecting the secondary fluid supply connects the secondary fluid supply to the valve chamber at the rear end of the housing.
The control sleeve has a rear portion terminating in a rear end, and a front portion. The front portion of the control sleeve is slidably and sealingly supported inside the rear portion of the striker. The rear portion of the control sleeve is slidably and sealingly received at least partially inside the valve chamber. The control sleeve provides continuous fluid communication between the means for operably connecting the primary fluid supply and the interior striker chamber. As a result, in response to supply of primary fluid the striker reciprocates between a forward position and a rearward position. In the forward position, the striker port is open between the interior striker chamber and the forward operating chamber. In the rearward position, the striker port is open between the forward operating chamber and the rearward operating chamber and the exhaust conduit.
Finally, the rear portion of the control sleeve includes a nodular lobe inside the valve chamber that sealingly engages an inner wall of the valve chamber and divides the valve chamber into the front valve chamber and the rear valve chamber. The nodular lobe of the rear portion of the control sleeve is movable between a forward position in response to pressurization of the rear valve chamber and a rearward position in response to depressurization of the rear valve chamber. This causes the front portion of the control sleeve to move between a forward position in which the striker hits the forward striker surface as it reciprocates, and a rearward position in which the striker hits the rearward striker surface as it reciprocates.
In yet another aspect, the invention is an impact-operated, ground-penetrating tool powered by a primary supply of pressurized fluid, and controlled between forward operating mode and a reverse operating mode by a second supply of pressurized fluid. The tool comprises a housing, a striker, a primary connecting assembly, a valve chamber, a secondary connecting assembly and a control sleeve. The housing having a front end, a rear end, and body defining an interior operating chamber with an inner surface, an exhaust conduit providing communication between the interior operating chamber and the outside of the tool, a forward striker surface, and a rearward striker surface.
A striker is reciprocally supported within the interior operating chamber of the housing between the forward and rearward striker surfaces. The striker has a forward end, a rear portion terminating in a rear end, and a striker body defining an interior striker chamber. The rear portion of the striker sealingly engages the inner surface of the interior operating chamber to divide the interior operating chamber into a forward operating chamber and a rearward operating chamber. The rearward operating chamber is continuous with the exhaust conduit and the striker body has at least one striker port to provide fluid communication between the forward operating chamber and the interior striker chamber.
The primary connecting assembly operably connects the primary fluid supply to the interior striker chamber. The valve chamber is located at the rear end of the housing and comprises a front valve chamber and a rear valve chamber. The secondary connecting assembly operably connects the secondary fluid supply to the rear valve chamber. The control sleeve has a rear portion terminating in a rear end, and a front portion.
The front portion of the control sleeve is slidably and sealingly supported inside the rear portion of the striker. The rear portion of the control sleeve is slidably and sealingly received at least partially inside the valve chamber. The sleeve provides continuous fluid communication between primary connecting assembly and the interior striker chamber. As a result, in response to supply of primary fluid the striker reciprocates between a forward position and a rearward position. In the forward position, the striker port is open between the interior striker chamber and the forward operating chamber. In the rearward position, the striker port is open between the forward operating chamber and the rearward operating chamber and the exhaust conduit.
Finally, the rear portion of the control sleeve includes a nodular lobe inside the valve chamber that sealingly engages an inner wall of the valve chamber and divides the valve chamber between the front valve chamber and the rear valve chamber. The nodular lobe of the rear portion of the control sleeve is movable between a forward position in response to pressurization of the rear valve chamber and a rearward position in response to depressurization of the rear valve chamber. This causes the front portion of the control sleeve to move between a forward position in which the striker hits the forward striker surface as it reciprocates, and a rearward position in which the striker hits the rearward striker surface as it reciprocates.
In another aspect, the invention is a reversible impact ground penetrating boring tool comprising a housing, a striker, a primary fluid supply assembly, a control sleeve, and a secondary fluid supply assembly. The housing has a rear end, and an interior chamber defining a forward striker surface and a rearward striker surface.
The striker has an external wall surrounding an interior striker chamber. The striker is slidably and sealingly receivable within the interior chamber of the housing and is adapted to reciprocally move between the forward striker surface and the rearward striker surface. The external wall of the striker and the interior chamber of the housing define an operating chamber. The primary fluid supply assembly is operably connectable to the striker and is adapted to provide pressurized primary fluid to the interior striker chamber. As a result, the striker will be driven in a reciprocal motion within the interior chamber of the housing when the pressurized primary fluid is supplied.
The control sleeve has a front portion, a rear portion terminating in a rear end, and an interior sleeve chamber defining a passage from the front portion to the rear portion. The valve fluid chamber is configured to have a first end and a second end and comprises a front valve chamber toward the first end and a rear valve chamber toward the second end. The front portion of the control sleeve is slidably and sealingly receivable within the interior striker chamber. The rear portion of the control sleeve is slidably and sealingly receivable within the valve fluid chamber at the rear end of the tool housing such that the rear portion of the control sleeve engages an inner wall of the valve chamber and divides the valve chamber between the front valve chamber and the rear valve chamber.
The rear portion of the control sleeve is adapted to move toward the first end of the valve fluid chamber during tool advancement. The rear portion of the control sleeve is adapted to move toward the second end of the valve fluid chamber during tool withdrawal. Additionally, the striker will impact the forward striker surface when the control sleeve is at the first end of the valve fluid chamber and the rearward striker surface when the control sleeve is at the second end of the valve fluid chamber.
The secondary fluid supply assembly is operably connectable to the rear valve fluid chamber. The rear valve fluid chamber is pressurized by the secondary fluid supply assembly. The rear valve fluid chamber is pressurized to move and hold the sleeve at the first end during tool advancement and the rear valve fluid chamber is depressurized to permit the control sleeve to move toward and remain at the second end during tool withdrawal.
In yet another aspect, the invention is an impact-operated, ground-penetrating drill assembly. The drilling assembly comprises a boring tool, a primary fluid supply system, and a secondary fluid supply system. The primary fluid supply system is adapted to supply pressurized fluid to power movement of the boring tool. The secondary fluid supply system is adapted to supply pressurized fluid to control movement of the boring tool between a forward operating mode and a reverse operating mode.
The boring tool comprises a housing, a striker, a manifold, a primary fluid inlet tube, a valve chamber, and a control sleeve. The housing has a front end, a rear end, and body defining an interior operating chamber with an inner surface and an exhaust conduit. The exhaust conduit provides communication between the operating chamber and the outside of the tool. Additionally, the housing comprises a forward striker surface, and a rearward striker surface.
The striker is reciprocally supported within the operating chamber of the housing between the forward and rearward striker surfaces. The striker has a forward end, a rear portion terminating in a rear end, and a striker body defining an interior striker chamber. The rear portion of the striker sealingly engages the inner surface of the operating chamber to divide the operating chamber into a forward operating chamber and a rearward operating chamber. The rearward operating chamber is continuous with the exhaust conduit. Additionally, the striker body has at least one striker port to provide fluid communication between the forward operating chamber and the interior striker chamber.
The manifold is located near the rear end of the housing and comprises a primary conduit connectable to the primary fluid supply system and a secondary conduit connectable to the secondary fluid supply system. The primary fluid inlet tube extends from the primary conduit of the manifold. Further, the valve chamber is configured to have a front valve chamber and a rear valve chamber. The rear valve chamber is in fluid communication with the secondary conduit in the manifold. The control sleeve has a rear portion, a front portion, and an interior sleeve chamber defining a passage between the rear portion and the front portion. The front portion of the control sleeve is slidably and sealingly supported inside the rear portion of the striker. The rear portion of the control sleeve is slidably and sealingly supported on the primary fluid inlet tube at least partially inside the valve chamber.
The control sleeve provides continuous fluid communication between the primary fluid inlet tube and the striker chamber. As a result, in response to a supply of primary fluid the striker reciprocates between a forward position in which the striker port is open between the interior striker chamber and the forward operating chamber and a rearward position in which the striker port is open between the forward operating chamber and the rearward operating chamber and exhaust conduit.
Finally, the rear portion of the sleeve includes a nodular lobe inside the valve chamber that sealingly engages an inner wall of the valve chamber and divides the valve chamber into the front valve chamber and the rear valve chamber. The nodular lobe of the rear portion of the control sleeve is movable between a forward position in response to pressurization of the rear valve chamber and a rearward position in response to depressurization of the rear valve chamber. As a result, the front portion of the sleeve moves between a forward position in which the striker hits the forward striker surface as it reciprocates and a rearward position in which the striker hits the rearward striker surface as it reciprocates.
In another aspect, the invention is a method of using an impact-operated, ground penetrating tool for a boring operation. The tool has a valve chamber and an interior striker chamber and a valve chamber. The valve chamber is configured to have a front valve chamber and a rear valve chamber. The method comprises operating the tool in a forward operating mode, maintaining the tool in the forward operating mode, and operating the tool in the reversed operating mode.
The tool is operated in the forward operating mode by substantially simultaneously pressurizing the rear valve chamber and the interior striker chamber with fluid. The tool is maintained in the forward operating mode by solely by pressurization of the rear valve chamber. Finally, the tool is operated in the reverse operating mode by substantially simultaneously pressurizing the interior striker chamber and depressurizing the rear valve chamber.
In still another aspect, the invention is an impact-operated ground-penetrating tool for use with a primary supply of pressurized fluid and a secondary supply of pressurized fluid. The tool comprises a housing, a striker, a valve chamber, and a control sleeve. The housing has a front end, a rear portion, and an interior operating chamber with a forward striker surface and a rearward striker surface. The rear portion of the housing includes a primary inlet adapted to receive the primary supply of pressurized fluid and a secondary inlet adapted to receive the secondary supply of pressurized fluid.
The striker is slidably and sealingly supported inside the operating chamber for reciprocal movement therein between the forward striker surface and the rearward striker surface. The striker has a forward impact surface adapted to impact the forward striker surface whereby the tool is operable in the forward mode. Additionally, the striker has a rear impact surface adapted to impact the rearward striker surface whereby the tool is operable in the rearward mode. The striker further comprises a rear end and an interior striker chamber opening at the rear end and ending a distance from the rear end.
The valve chamber in formed in the rear portion of the housing and is configured to have a first end and a second end, and comprises a front valve chamber and a rear valve chamber. The front valve chamber is toward the first end and the rear valve chamber is toward the second end. The rear valve chamber is in fluid communication with the secondary inlet. The control sleeve has a front portion terminating in an open front end defining a primary fluid surface. Additionally, the control sleeve has a rear portion terminating in an open rear end defining a secondary fluid surface. Further, the control sleeve has a sleeve passage therethrough continuous with the front end and the rear end thereof.
The rear portion of the control sleeve is sealingly and slidably supported inside the valve chamber such that the rear portion of the control sleeve engages an inner wall of the valve chamber and divides the valve chamber into the front valve chamber and the rear valve chamber, for movement therein in response to pressure in the rear valve chamber from the secondary supply of pressurized fluid. The control sleeve is movable between a forward position in which the rear portion approaches the first end of the valve chamber and a rearward position in which the rear portion approaches the second end of the valve chamber. The sleeve passage is in constant fluid communication with the primary inlet.
The rear portion of the striker is slidingly and sealingly supported on the front portion of the control sleeve so that the interior striker chamber is in fluid communication with the sleeve passage whereby the striker is movable in response to pressure from the primary supply of pressurized fluid. Additionally, the rear portion of the striker comprises a fluid port to provide fluid communication between the interior striker chamber and the operating chamber. The port is positioned so that when the control sleeve is in the forward position the striker operates in the forward mode and so that when the control sleeve is in the reverse position the striker operates in the rearward mode.
The primary fluid surface on the control sleeve is adapted to receive pressure from the primary supply of pressurized fluid in the striker chamber to move the control sleeve toward the rearward position. Additionally, the secondary fluid surface is adapted to receive pressure from the secondary supply of pressurized fluid in the valve chamber to move the control sleeve toward forward position. However, a cross-sectional area of the secondary fluid surface taken perpendicular to the longitudinal axis of the control sleeve is greater than a cross-sectional area of the primary fluid surface taken perpendicular to the longitudinal axis of the control sleeve so that pressure from the secondary fluid acting on the secondary fluid surface is sufficient to overcome the pressure of the primary fluid on the primary fluid surface and maintain the control sleeve in the forward position.